failed Apple wired keyboard

I had a situation where I could not access my computer, iMac OS10.15.5, there was nothing I could do. Purely on speculation, I swapped keyboards with another similar keyboard, and it worked! I swapped back and forth between the two and kept proving that the original keyboard would not work. The original keyboard is one that came with my new iMac, April 2019, and had only normal use. I should add that it did not fail completely, I still got some expected response from some function keys, but nothing from the alfpha or numeric keys. Is this type of failure common and what could possibly cause it?

No, I didn't spill and liquid on the keyboard or attempt to clean it! Thanks , Victor